Lateral static overload on immediately restored implants decreases the osteocyte index in peri-implant bone: a secondary analysis of a pre-clinical study in dogs

Gene expression, micro-CT and histomorphometrical analysis of sinus floor augmentation with biphasic calcium phosphate and deproteinized bovine bone mineral: A randomized controlled clinical trial

AIMS

The aim of this randomized controlled clinical trial was to compare the gene expression, micro-CT, histomorphometrical analysis between biphasic calcium phosphate (BCP) of 70/30 ratio and deproteinized bovine bone mineral (DBBM) in sinus augmentation.

MATERIALS AND METHODS

Twenty-four patients in need for sinus floor augmentation through lateral approach were randomized into BCP 70/30 ratio or DBBM. After at least 6 months of healing, a total of 24 bone specimens were collected from the entire height of the augmented bone at the area of implant placement and underwent micro-CT, histomorphometric and gene expression analysis. The 12 bone specimens of BCP 70/30 ratio were equally allocated to micro-CT and histologic analysis (test group, n = 6) and gene expression analysis (test group, n = 6). Similarly, the 12 bone specimens of DBBM were also allocated to micro-CT and histologic analysis (control group, n = 6) and gene expression analysis (control group, n = 6). The newly formed bone, remaining graft materials and relative change in gene expression of four target genes were assessed.

RESULTS

The micro-CT results showed no statistically significant difference in the ratio of bone volume to total volume (BV/TV ratio) for the two groups (BCP 41.51% vs. DBBM 40.97%) and the same was true for residual graft material to total volume (GV/TV ratio, BCP 9.97% vs. DBBM 14.41%). Similarly, no significant difference was shown in the histological analysis in terms of bone formation, (BCP 31.43% vs. DBBM was 30.09%) and residual graft area (DBBM 40.76% vs. BCP 45.06%). With regards to gene expression, the level of ALP was lower in both groups of bone grafted specimens compared with the native bone. On the contrary, the level of OSX, IL-1B and TRAP was higher in augmented bone of both groups compared with the native bone. However, the relative difference in all gene expressions between BCP and DBBM group was not significant.

CONCLUSIONS

The BCP, HA/β-TCP ratio of 70/30 presented similar histological and micro-CT outcomes in terms of new bone formation and residual graft particles with DBBM. The gene expression analysis revealed different gene expression patterns between augmented and native bone, but showed no significant difference between the two biomaterials.

Guided Bone Regeneration with Occlusive Titanium Barrier: A Case Report and Clinical Considerations

The need to obtain adequate bone volumes for prosthetic rehabilitation supported by implants, using different techniques and materials, represents an urgent need in modern dentistry. We report a case regarding the management of implant-prosthetic rehabilitation of the first and second upper right molars, in which no less than 4 mm of crestal bone remained to insert two implants. Regeneration of the residual bone was previously performed using a customized titanium barrier and a filler of a blood clot with tricalcium beta phosphate. The bone gain (3 mm) was evaluated by comparing CBCT images, while the implant stability (mean 70) was assessed with the ISQ measurement. A regenerated bone sample was taken for histological analysis. Guided bone regeneration obtained with a titanium barrier and blood clot allowed for the insertion of stable implants in a mature bone without heterologous material.

The impact of deproteinized bovine bone particle size on histological and clinical bone healing outcomes in the augmented sinus: A randomized controlled clinical trial

OBJECTIVE

The effect of different deproteinized bovine bone mineral (DBBM) particle sizes on bone healing in maxillary sinus floor augmentation remains unclear. This study compared the newly formed tissue and angiogenesis-related bone healing after sinus floor augmentation using large or small DBBM particles.

MATERIALS AND METHODS

Overall 32 patients were randomly divided into two groups using either large (1-2 mm) or small (0.25-1 mm) DBBM particles for sinus floor augmentation. After 6 months, the mineralized tissue volume was calculated using micro-computed tomography (micro-CT) analysis. The newly formed tissue composition was histomorphometrically analyzed. Angiogenesis was also examined by means of vascular endothelial growth factor (VEGF) expression. Implant failure and marginal bone loss were measured at a 1-year follow-up. Statistical analysis was performed using independent samples t-test.

RESULTS

Micro-CT analysis demonstrated that grafting with large particles resulted in higher bone volume (6.99 ± 2.72 mm³ , p = 0.002) and Bone Volume/Tissue Volume (0.25 ± 0.1, p = 0.03) compared with small particles (3.76 ± 1.83 mm³ and 0.14 ± 0.13, respectively). Small particles showed higher non-mineralized tissue volume (26.31 mm³ ) compared with large particle group (17.4 ± 5.34 mm³ ) with p = 0.001. The histological data revealed significantly higher area of newly formed bone (32.15% ± 14.04% for the large particle and 15.99% ± 14.12% for the small particle groups, p = 0.004). Likewise, non-mineralized tissue was significantly greater in the small particle group (66.48% ± 20.97%) compared with the large particle group (44.36%, p = 0.016). Moreover, use of large particles resulted in a significantly higher VEGF staining intensity score and VEFG positive cells. No implant failure was recorded in both groups, while no difference was found in terms of marginal bone loss at the 1-year follow-up.

CONCLUSIONS

Sinus floor augmentation using large DBBM particles resulted in more angiogenesis expression, higher bone volume, and new bone formation at 6 months after sinus augmentation. However, clinical outcomes with regards to implant placement were similar in both groups.

A temporospatial histomorphometric analysis of bone density adjacent to acid-etched self-tapping dental implants with an external hexagon connection in the female baboon

OBJECTIVE

To characterize osseointegration as the percent of bone-implant contact (%BIC) along the surface (0.0 mm) as well as at surface profiles 0.5 mm and 1.0 mm lateral to the implant, determining any differences between early occlusally loaded and non-loaded implants.

MATERIAL AND METHODS

In ten adult female baboons, 120 dental implants were randomly placed in opposing mandibular and maxillary locations. Eighty sites had two groups of healing (no load) of either 1 (n = 40) or 2 (n = 40) months leading to 3 months of functional loading. These sites received full acid-etched surface implants. The 40 control implants represented healing only periods (no load) for 1 (n = 10), 2 (n = 10), 4 (n = 10), and 5 (n = 10) months. These implants were of a vertically split surface texture design (acid-etched and machined). Block sections and photomicrographs were obtained. Blinded histometric analyses determined the %BIC via a superimposed template.

RESULTS

The unloaded groups (1, 2, and 4 months) had higher %BIC compared to the 5-month group (p < 0.0001). The loaded groups exhibited mean bone densities of 59.2% and 55.5% (1-month healing at 0.5 mm and 1.0 mm, respectively) and 61.0% and 57.1% (2-month healing at 0.5 mm and 1.0 mm, respectively) with no significant difference between healing time (p = 0.4118).

CONCLUSION

There was a lateral increase in %BIC in the loaded compared to unloaded groups.

CLINICAL RELEVANCE

The decrease in bone densities at the 5-month unloaded group suggests that there is a critical earlier time period when dental implants should be placed into functional load.